Many percutaneous intravascular procedures use a guidewire as an initial approach of accessing a particular vessel. Once the distal guidewire tip has been placed at the area of interest, a catheter is passed over the wire from the proximal end using it as a guide to track the catheter into that vessel. Conventional intravascular procedures are conducted using X-ray and/or ultrasound imaging technology to facilitate catheter guidance.
Magnetic resonance imaging (MRI) has several distinct advantages over X-ray imaging technology, such as excellent soft-tissue contrast, the ability to define any tomographic plane, and the absence of ionizing radiation exposure. In addition, MRI offers several specific advantages that make it especially well suited for guiding various devices used in diagnostic and therapeutic procedures including: 1) real-time interactive imaging, 2) direct visualization of critical anatomic landmarks, 3) direct high resolution imaging, 4) visualization of a device-tissue interface, 5) the ability to actively track device position in three-dimensional space, and 6) elimination of radiation exposure.
Induced RF currents (referred to as RF coupling) on guide wires and other elongated devices utilized in MRI environments can be problematic. Such RF coupling may cause significant image artifacts, and may induce undesired heating and cause local tissue damage. To reduce the risk of tissue damage, it is desirable to reduce or prevent patient contact with cables and other conductive devices in an MRI environment. Such contact, however, may be unavoidable in some cases. For devices that are inserted inside the body, such as intravascular devices, the risk of tissue damage may increase.